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Incoherent High-Resolution Z-Contrast Imaging of Silicon and Gallium Arsenide Using HAADF-STEM

Published online by Cambridge University Press:  10 February 2011

Y Kotaka
Affiliation:
FUJITSU LABORATORIES LTD., Atsugi, Japan
T. Yamazaki
Affiliation:
Department of Physics, Science University of Tokyo, Tokyo, Japan
Y Kikuchi
Affiliation:
FUJITSU LABORATORIES LTD., Atsugi, Japan
K. Watanabe
Affiliation:
Tokyo Metropolitan College of Technology, Tokyo, Japan
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Abstract

The high-angle annular dark-field (HAADF) technique in a dedicated scanning transmission electron microscope (STEM) provides strong compositional sensitivity dependent on atomic number (Z-contrast image). Furthermore, a high spatial resolution image is comparable to that of conventional coherent imaging (HRTEM). However, it is difficult to obtain a clear atomic structure HAADF image using a hybrid TEM/STEM. In this work, HAADF images were obtained with a JEOL JEM-2010F (with a thermal-Schottky field-emission) gun in probe-forming mode at 200 kV. We performed experiments using Si and GaAs in the [110] orientation. The electron-optical conditions were optimized. As a result, the dumbbell structure was observed in an image of [110] Si. Intensity profiles for GaAs along [001] showed differences for the two atomic sites. The experimental images were analyzed and compared with the calculated atomic positions and intensities obtained from Bethe's eigen-value method, which was modified to simulate HAADF-STEM based on Allen and Rossouw's method for convergent-beam electron diffraction (CBED). The experimental results showed a good agreement with the simulation results.

Type
Research Article
Copyright
Copyright © Materials Research Society 2001

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